Whitewash


Whitewash

Whitewash, or calcimine, kalsomine, or calsomine is a very low cost type of paint made from slaked lime (calcium hydroxide) and chalk (whiting). Various other additives have also been used.

Whitewash

Whitewash cures through a reaction with carbon dioxide in the atmosphere to form calcium carbonate in the form of calcite, a reaction known as carbonatation.

When the paint initially dries it is uncured, and has almost no strength. It takes a period of anything up to a few days, depending on climate, to harden.

It is usually applied to exteriors. Occasionally it is colored and used on interiors, such as the hallways of apartment buildings, but it is not popular for this as it can rub off onto clothing to a small degree.

Whitewash is especially effective on adobe-like materials because it is absorbed easily and the resultant chemical reaction hardens the substrate. Also whitewash and adobe are both very low cost building materials.

The coating has antimicrobial properties that provide hygienic and sanitary benefits for animal barns. [Fiasco Farm, White Wash, http://fiascofarm.com/recipes/whitewash.html]

In the middle of the 20th century, when family farms with dairy barns were common in the Upper Midwest of the USA, whitewash was a necessary part of routine barn maintenance.

Limewash

Lime wash is pure slaked lime in water. It produces a unique surface glow due the to refraction of calcite crystals. Limewash and whitewash both cure to become the same material.

When limewash is initially applied it has very low opacity, which can lead novices to overthicken the paint. Drying increases opacity, and subseqent curing increases opacity again.

Additives

Additives that have been used include water glass, glue, egg white, Portland cement, salt, soap, milk, flour, earth, blood.

Whitewash is sometimes coloured with earths to achieve colours spanning the range of broken white, cream, yellow and a range of browns.

Historically pig's blood was added to give the colour Suffolk pink, a colour still widely used on house exteriors in some areas of the UK. Animal blood also further reinforces the earth based substrate to some degree.

Pozzolanic materials are occasionally added to give a much harder wearing paint finish. However paint with these added has a short open time, so pozzolan can only be added at point of use.

Linseed oil is sometimes added (typically 0.5-2%) to improve adhesion on difficult surfaces.

Cement addition makes a harder wearing paint in white or grey. Open time is short, so this is added at point of use.

Dilute glues improve paint toughness.

Wheat flour has been used as a strength enhancing binder. Salt is usually added to prevent the flour going mouldy later in damp conditions. The use of salt brings its own issues.

Cost

Simple lime paints are very low cost. A 25kg bag of lime makes around 100kg of paint, and costs around £6 in the UK (2008).

References

External links

* [http://fiascofarm.com/recipes/whitewash.html Farm recipe for whitewash, with details]
* Lighthouse keeper's [http://www.crisppointlighthouse.org/formula.html formula for White Wash] at Crisp Point Light.
* [http://www.chicora.org/whitewash.pdf Types of whitewash]


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Look at other dictionaries:

  • whitewash — ► NOUN 1) a solution of lime and water or of whiting, size, and water, used for painting walls white. 2) a deliberate concealment of someone s mistakes or faults. 3) a victory by the same side in every game of a series. ► VERB 1) paint with… …   English terms dictionary

  • Whitewash — White wash , v. t. [imp. & p. p. {Whitewashed}; p. pr. & vb. n. {Whitewashing}.] [1913 Webster] 1. To apply a white liquid composition to; to whiten with whitewash. [1913 Webster] 2. To make white; to give a fair external appearance to; to clear… …   The Collaborative International Dictionary of English

  • whitewash — [hwīt′wôsh΄, wīt′wôsh΄] n. 1. a mixture of lime, whiting, size, water, etc., for whitening walls, etc. 2. a cosmetic formerly used for making the skin fair 3. a) a glossing over or concealing of faults or defects in an effort to exonerate or give …   English World dictionary

  • Whitewash — White wash , n. [1913 Webster] 1. Any wash or liquid composition for whitening something, as a wash for making the skin fair. Addison. [1913 Webster] 2. A composition of line and water, or of whiting size, and water, or the like, used for… …   The Collaborative International Dictionary of English

  • whitewash — A procedure set out in Appendix 1 to the City Code on Takeovers and Mergers by which the requirement for a mandatory offer under Rule 9 is waived by approval by target shareholders. Related links merger stakebuilding …   Law dictionary

  • whitewash — (v.) 1590s, to wash a building surface with white liquid, from WHITE (Cf. white) + WASH (Cf. wash). Figurative sense of to cover up, conceal is attested from 1762. Related: Whitewashed; whitewashing. The noun is recorded from 1690s …   Etymology dictionary

  • whitewash — vb whiten, gloze, gloss, *palliate, extenuate Analogous words: *disguise, cloak, mask, dissemble, camouflage: condone, *excuse …   New Dictionary of Synonyms

  • whitewash — [v] cover up the truth blanch, camouflage, conceal, exonerate, extenuate, gloss over, launder*, liberate, make light of*, paint, palliate, sugarcoat*, suppress, varnish, veneer, vindicate, white, whiten; concepts 49,63 Ant. expose, reveal, tell… …   New thesaurus

  • whitewash — [[t](h)wa͟ɪtwɒʃ[/t]] whitewashes, whitewashing, whitewashed 1) N UNCOUNT Whitewash is a mixture of lime or chalk and water that is used for painting walls white. 2) VERB If a wall or building has been whitewashed, it has been painted white with… …   English dictionary

  • whitewash — 1. tv. to make something look better than it really is; to conceal something bad. □ Now, don’t try to whitewash his incident. Open up about it. □ The mayor’s office tried to whitewash the whole affair. 2. n. an act or campaign of covering up… …   Dictionary of American slang and colloquial expressions


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